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From: dewar@gnat.com (Robert Dewar)
Newsgroups: comp.lang.ada
Subject: Re: Localized Variable Declaration
Date: 2 Jun 2002 08:20:19 -0700
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Darren New <dnew@san.rr.com> wrote in message news:<3CF79DFC.50613FAF@san.rr.com>...
> procedure .... is
>   begin
>     put_line("write two numbers");
>     declare
>       a : integer := read(...);
>       b : integer := read(...);
>       c : float := a * b * 42.42;
>     begin
>       put_line("answer = " & c'img);
>     end;
>   end;
> 
> or maybe something vaguely like that. :-)

well if we are going to give examples of good style to teach people
what Ada should look like, let's use good
style. There are two objections to the above. First it
has non-standard layout. There is no good reason for
using a layout other than the one recommended in the
RM in a case like this. Second, people overuse variables
all the time, and that's lazy (the latest versions of GNAT
warn you when you do this. Third, the assignment to C 
misleadingly implies that "mixed mode" artithmetic is allowed. Fourth,
the debugging attribute 'Img should not be used in a context like
this. Fifth, it is really good style to repeat procedure identifiers
in the end line. Sixth, it is better to copy the capitalization of
identifiers from the standard libraries. That's a lot of problems in a
few lines of code (I encourage everyone to compile code before
publishing here on the news group :-)

So let's correct that and write something that makes the
original point (which was valid and appropriately stated)
with correct code in good style:

> procedure .... is
> begin
>   Put_Line("write two numbers");
>   declare
>     a : constant Integer := Read (...);
>     b : constant Integer := Read (...);
>     c : constant Float := Float (a) * Float (b) * 42.42;
>   begin
>     Put_Line ("answer = " & Float'Image (c));
>   end;
> end ....;